Transcript How and why Gas Exchange happens:

How and why Gas Exchange
happens:
Location: The alveoli
Method: Diffusion
KEY WORDS:
• Partial pressure: In a mixture of
gases such as air or blood, each gas
accounts for a portion of the total
pressure the mixture produces. The
amount of pressure each gas
contributes is the partial pressure.
• Oxygen that you breathe in from the
atmosphere when it reaches your
alveoli has a partial pressure of PO2=
104mm Hg.
• The partial pressure of Oxygen in
your bloodstream from this point is
only 40mm Hg.
 FIRST- why is the blood stream partial
pressure of oxygen so low?
1. When blood reaches the alveolus / lungs the
blood is oxygen poor- it has depleted its oxygen
source to the rest of the body and needs to
“pick up more”.
Diffusion of Gases:
How does this happen?
 SECOND- where will the oxygen
want to diffuse to? Think about what
we know about diffusion already.
2. The oxygen will diffuse from an area of high concentration
to low or from the alveoli into the blood stream. Which
will now make it oxygen rich and travel to other tissues
and cells.
• Explain than what is going
on with the Carbon
dioxide?
• Why is carbon dioxide
higher in the blood
capillaries?
• With the help of diffusion
where does the Carbon
dioxide go?
How does pressure or
altitude affect breathing?
WHY?
• Why do my ears pop? If you've ever been to the top of a
tall mountain, you may have noticed that your ears pop
and you need to breathe more often than when you're at
sea level. As the number of molecules of air around you
decreases, the air pressure decreases. This causes your
ears to pop in order to balance the pressure between the
outside and inside of your ear. Since you are breathing
fewer molecules of oxygen, you need to breathe faster to
bring the few molecules there are into your lungs to make
up for the deficit.
LUNG CAPACITIES
KEY TERMS:
• Respiratory cycle: One inspiration plus one
expiriation. (Breathe in- breathe out)
• Resting Tidal volume- the normal amount of air
that enters the lungs and leaves the lungs during a
respiratory cycle.
• The average is about 500 milliliters of air per breath in
and the same amount out.
• During Tidal
volume you do
not use the total
amount of
space in your
lungs! They
only use about
75-80%
• Inspiratory Reserve Volume: When you take a
deep breath in to hold more air than a usual
breath. “Forced inhalation”.
• Expiratory Reserve Volume: Forced
expiration. Expelling air beyond the tidal
volume. Even after the most forceful exhale
however you still have air left in your lungs.
• This left over air is called the Residual Volume.
KEY TERMS:
• Vital Capacity: Combing the tidal volume with
both the inspiratory reserve volume and the
expiratory reserve volume.
• Total Lung Capacity: The vital capacity plus the
residual volume. All the possible air that can come
into or out of the lungs, including the air that never
leaves the lungs.
KEY TERMS:
Fill in the following table with the
appropriate terms: